Conventionally, in an environment of viewing and listening to video and audio by connecting a television receiver (hereafter called “television”) to a set top box, there are cases of viewing and listening to video and audio by further connecting a Digital Versatile Disc (DVD) player, and cases of listening to audio by further connecting an external AV amplifier and an external speaker, and outputting the audio from the speaker. In an Audio/Visual (AV) system such as this, in order to operate the respective devices, a user needs to switch among, and operate, remote controllers (hereafter called “controller”) corresponding to each of the devices. Furthermore, between viewing and listening to video and audio outputted by the set top box and viewing and listening to video and audio outputted by the DVD player, the user needs to switch the input of the television. In addition, in order to use the respective functions included in the respective devices, such as operation of an electronic program guide, the user needs to perform troublesome operations such as switching among controllers corresponding to the devices.
As one method for solving this problem, a function called Consumer Electronics Control (CEC) has been defined in High-Definition Multimedia Interface (HDMI) (for example, see Non-Patent Reference 1). This is a function in which a television and various AV devices are connected by an HDMI cable, and transmit and receive CEC commands to each other via a CEC bus included in the HDMI cable. CEC defines a command which is transmitted with the destination of the command being specified, and a broadcast command for notifying a command to all CEC-compliant devices connected by HDMI, and communication is carried out using a combination of these commands. The CEC command, as shown in FIG. 1, includes the transmission destination device logical address, transmission destination device logical address, an operating code, and an operand.
Non-Patent Reference 1 defines One Touch Play, Routing Control, Device Menu Control, Remote Control Pass Through, and so on, as applications using a CEC command.
Hereinafter, device control in the conventional remote control system shall be described using FIG. 2.
As shown in FIG. 2, a remote control system includes a television 101, an AV amplifier 102, a DVD player 103, an external speaker 104, a set top box 105, and a controller 106.
The television 101 is a device for outputting video and audio outputted from a device connected via an HDMI cable.
The AV amplifier 102, to which HDMI input terminal the DVD player 103 is connected, receives video and audio from the DVD player 103 via the HDMI input terminal, and outputs the video outputted from the DVD player 103 to the television 101 connected to an HDMI output terminal, while outputting audio from the external speaker 104. Furthermore, the AV amplifier 102 can switch between the input from another device not shown in the diagram and the input from the DVD player 103, and output video to the television 101.
The DVD player 103 is a device which decodes video content recorded on a DVD, and outputs video and audio via the HDMI cable.
The set top box 105 is a device which outputs video and audio of a cable television broadcast, via the HDMI cable.
In the above-described configuration, when the DVD player 103 starts playback, for example, the DVD player 103 transmits a <Text View On> command or an <Image View On> command to the television 101, and transmits an <Active Source> command indicating the start of video output. The television 101 and the AV amplifier 102 which receive the respective commands, each perform input switching automatically so that the video of the DVD player 103 is outputted based on the parameters of the commands. Furthermore, when the television 101 is OFF, the television automatically turns ON.
Furthermore, when the user operates the DVD player 103 by operating the controller 106 of the television 101, the signal transmitted from the controller 106 is received by the television 101, and the television 101 transmits a command corresponding to the signal of the controller, to the DVD player 103. Upon receiving the command, the DVD player 103 performs the corresponding operation thereby enabling the user to operate the DVD player 103 using the controller of the television 101.
Furthermore, another example of device control in the conventional remote control system shall be described using FIG. 3.
As shown in FIG. 3, a remote control system includes a television 301, a DVD player 302, a DVD recorder 303, a set top box 304, and a controller 305.
The television 301 is a device for outputting video and audio outputted from a device connected via an HDMI cable.
The DVD player 302 is a device which decodes video content recorded on a DVD, and outputs video and audio via the HDMI cable.
The DVD recorder 303, like the DVD player 302, is a device which decodes video content recorded on a DVD, and outputs video and audio via the HDMI cable. Furthermore, the DVD recorder 303 has a function for receiving and encoding video and audio, and recording the encoded video and audio on a recording DVD.
The set top box 304 is a device which outputs video and audio of a cable television broadcast, via the HDMI cable.
Devices connected through the HDMI cable obtain a physical address by Display Data Channel (DDC) communication defined in the HDMI Standard. Here, DDC communication is a function for inquiries: from a device (called a source device) connected by the HDMI cable, which transmits video and audio; to a device (called a sink device) which receives video and audio; regarding the device-type information of the sink device, the reproducible video and audio format, the physical address assigned to the source device, and so on. The logical address is an address given according to terminals connected by the HDMI cable, and is, for example, 1.0.0.0 when connected to a first terminal of the television, and 2.0.0.0 when connected to the second terminal.
In the configuration indicated in FIG. 3, when the DVD player 302 starts playback, for example, the DVD player 302 transmits an <Active Source> command, which is a broadcast command indicating the start of video and audio output, with the physical address of the transmission source device as a parameter. Upon receiving the command, the television 301 automatically performs input switching, based on the parameter of the <Active Source> command, so that the video of the DVD player 302 is outputted. Furthermore, when the television 301 is OFF, the television automatically turns ON.
Furthermore, when the user operates the DVD player 302 by operating the controller 305 of the set top box 304, the signal transmitted from the controller 305 is received by the set top box 304. The set top box 304 transfers a CEC command corresponding to the signal received from the controller 305, to the DVD player 302. The DVD player 302 receiving the command performs an operation corresponding to the command. With this, the user is able to operate the DVD player 302 by operating the controller 305 of the set top box 304.
Furthermore, according to Patent Reference 1, in an AV system including an AV bus for transmitting data signals such as a command, a video signal, and an audio signal, between a television and respective devices in the AV system, the respective devices are controlled by operating the television.
Hereinafter, the device control in Patent Reference 1 shall be described using FIG. 4.
Respective devices in an AV system are connected by an AV bus, and a signal passing through the bus has the form of a packet. Furthermore, each packet includes a transmission source address indicating the device that transmitted the data, and a destination address indicating the destination of the data.
A television 311 receives a command transmitted from a controller 315, and transmits a command to the AV bus according to the details of the received command.
When receiving the command from the AV bus, each of a DVD player 312, a DVD recorder 313, and a set top box 314 analyzes and executes the command when the destination address of the command is addressed to it. Furthermore, when the command is not addressed to it, the command is disregarded without being analyzed.
Hereinafter, the operation in the case where the DVD player 312 plays back video recorded on a DVD, and displays the video on the television 311, in the AV system in Patent Reference 1 shall be described.
First, when the user presses a power ON button of the controller 315, a signal indicating power ON is transmitted. Upon receiving the signal, the television 311 performs the checking of the connection state of devices connected to the AV bus, the detection of malfunctions, and so on.
Next, when the user presses a menu button of the controller 315, the television 311 displays a first control window on a screen. Icons indicating AV devices such as the DVD player, and a cursor are displayed on the first control window. The user can move the cursor by pressing UP, DOWN, LEFT, and RIGHT buttons on the controller 315, and activate, in the television 311, a program corresponding to the icon indicated by the cursor, by pressing an ENTER button.
Next, when the user points the cursor to the icon indicating the DVD player and presses the ENTER button, the television 311 displays a second control window. Icons for setting the operating mode of the DVD player, such as playback and stop, and a cursor are displayed on the second control window. By performing the same operation as in the case of the first control window, the user can activate a program corresponding to the icon indicated by the cursor. In the case of performing playback using the DVD player 312, the user points the cursor to the icon indicating playback and presses the ENTER button. Then, the television 311 generates a command for setting the DVD player 312 to the playback mode, adds a destination address indicating the DVD player 312, and transmits the command to the AV bus.
The DVD player 312 checks the destination address of the command transmitted by the AV bus and, when the destination address indicates the DVD player 312, analyzes the details of the command and executes the command. In the case where the received command is a command for setting the playback mode, the DVD player 312 starts playback of the DVD.    Non-Patent Reference 1: High-Definition Multimedia Interface Specification Version 1.3a    Patent Reference 1: Japanese Unexamined Patent Application Publication No. 5-260554